How does Newton's Third Law relate to rocketry?

Newton's Third Law states that for every action, there is an equal and opposite reaction. This principle is directly applicable to rocketry. When a rocket engine fires, it expels exhaust gases at high speed in one direction. According to Newton's Third Law, the action of the gases being expelled creates a reaction that propels the rocket in the opposite direction. This is the fundamental operating principle of rocket propulsion, where the thrust produced by the rocket motors pushes the rocket forward while the exhaust jets move in the opposite direction.

In contrast to the other options, they do not align with the foundational principles of rocketry. Air resistance does not facilitate a rocket's flight; instead, rockets operate primarily in the vacuum of space where air resistance is not relevant. The claim that a rocket's motion is solely due to gravitational pull oversimplifies the dynamics of flight, as propulsion generated by the rocket engines is crucial for overcoming gravitational forces. Lastly, the assertion that a rocket does not need thrust to fly contradicts the very nature of how rockets are designed to operate, as thrust is essential for generating lift and forward motion.